Dogcows Code - chaz/githead/blob - githead.c

   1
   2 /*
   3  * Get the name of the current git branch (pointed to by HEAD) and print it
   4  * out, color-coded to show if any working files are dirty.  This would
   5  * ideally be implemented as a shell script, but I wrote it in C because it
   6  * needs to be fast!  And we all know C is fast, amiright?
   7  *
   8  * Also reads in regular expressions (one per line) matching paths that
   9  * should be ignored.  Each regex is matched against the top-level
  10  * directory path of the repository.  If it matches, nothing is printed.
  11  * It is a good idea to ignore repositories on slow (remote) disks.
  12  *
  13  * Example usage (bash):
  14  * PS1='\u@\h \w$(githead <~/.nogitprompt) $ '
  15  *
  16  * Written 04 June 2012 by Charles McGarvey.
  17  */
  18
  19 const char* ansi_codes = "0;36";
  20 const char* ansi_codes_dirty = "0;31";
  21
  22 #include <errno.h>
  23 #include <regex.h>
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28
  29 #include <sys/types.h>
  30 #include <sys/wait.h>
  31
  32 int main(int argc, char* argv[])
  33 {
  34     char buf[4096];
  35
  36     char*   branch = NULL;
  37     int     dirty = 0;
  38
  39     fclose(stderr);     // usually do not want any extra junk printed
  40
  41     int p[2];
  42     if (pipe(p) == -1) {
  43         fprintf(stderr, "pipe failed: %s\n", strerror(errno));
  44         return 1;
  45     }
  46
  47     pid_t pid1 = fork();
  48     if (pid1 == -1) {
  49         fprintf(stderr, "fork failed: %s\n", strerror(errno));
  50         return 1;
  51     }
  52     if (pid1 == 0) {
  53         char* args[] = {"git", "rev-parse", "--show-toplevel", NULL};
  54         if (dup2(p[1], 1) == -1) {
  55             fprintf(stderr, "dup2 failed: %s\n", strerror(errno));
  56         }
  57         execvp(args[0], args);
  58         return 0;
  59     }
  60
  61     close(p[1]);
  62
  63     int status;
  64     while (waitpid(pid1, &status, 0) < 0) {
  65         if (errno != EINTR) {
  66             fprintf(stderr, "waitpid failed: %s\n", strerror(errno));
  67             return 1;
  68         }
  69     }
  70     if (WEXITSTATUS(status) == 0) {
  71         ssize_t bytes = read(p[0], buf, sizeof(buf));
  72         if (bytes < 0) {
  73             fprintf(stderr, "read failed: %s\n", strerror(errno));
  74             return 1;
  75         }
  76         buf[bytes-1] = '\0';
  77
  78         char regbuf[4096];
  79         while (gets(regbuf)) {
  80             char errbuf[4096];
  81             regex_t re;
  82             int err = regcomp(&re, regbuf, REG_EXTENDED | REG_ICASE | REG_NOSUB);
  83             if (err != 0) {
  84                 regerror(err, &re, errbuf, sizeof(errbuf));
  85                 fprintf(stderr, "regcomp failed: %s\n", errbuf);
  86                 continue;
  87             }
  88             if (regexec(&re, buf, 0, NULL, 0) == 0) {
  89                 return 0;
  90             }
  91             regfree(&re);
  92         }
  93     }
  94     else {
  95         fprintf(stderr, "git failed; bailing out...\n");
  96         return 1;
  97     }
  98
  99     pid_t pid2 = fork();
 100     if (pid2 == -1) {
 101         fprintf(stderr, "fork failed: %s\n", strerror(errno));
 102         return 1;
 103     }
 104     if (pid2 == 0) {
 105         char* args[] = {"git", "diff", "--no-ext-diff", "--quiet", "--exit-code", NULL};
 106         execvp(args[0], args);
 107         return 0;
 108     }
 109
 110     if (pipe(p) == -1) {
 111         fprintf(stderr, "pipe failed: %s\n", strerror(errno));
 112         return 1;
 113     }
 114
 115     pid_t pid3 = fork();
 116     if (pid3 == -1) {
 117         fprintf(stderr, "fork failed: %s\n", strerror(errno));
 118         return 1;
 119     }
 120     if (pid3 == 0) {
 121         char* args[] = {"git", "symbolic-ref", "HEAD", NULL};
 122         if (dup2(p[1], 1) == -1) {
 123             fprintf(stderr, "dup2 failed: %s\n", strerror(errno));
 124         }
 125         execvp(args[0], args);
 126         return 1;
 127     }
 128
 129     close(p[1]);
 130
 131     while (waitpid(pid3, &status, 0) < 0) {
 132         if (errno != EINTR) {
 133             fprintf(stderr, "waitpid failed: %s\n", strerror(errno));
 134             return 1;
 135         }
 136     }
 137     if (WEXITSTATUS(status) == 0) {
 138         ssize_t bytes = read(p[0], buf, sizeof(buf));
 139         if (bytes < 0) {
 140             fprintf(stderr, "read failed: %s\n", strerror(errno));
 141             return 1;
 142         }
 143         buf[bytes-1] = '\0';
 144         branch = buf + 11;
 145     }
 146
 147     while (waitpid(pid2, &status, 0) < 0) {
 148         if (errno != EINTR) {
 149             fprintf(stderr, "waitpid failed: %s\n", strerror(errno));
 150             return 1;
 151         }
 152     }
 153     dirty = (WEXITSTATUS(status) != 0);
 154
 155     if (branch) {
 156         if (dirty) {
 157             printf("\033[%sm[%s]\033[0m", ansi_codes_dirty, branch);
 158         }
 159         else {
 160             printf("\033[%sm[%s]\033[0m", ansi_codes, branch);
 161         }
 162     }
 163
 164     return 0;
 165 }
 166